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#include "flutter/sky/engine/platform/graphics/StrokeData.h"

#include "flutter/sky/engine/platform/graphics/skia/SkiaUtils.h"
#include "flutter/sky/engine/wtf/OwnPtr.h"
#include "flutter/sky/engine/wtf/PassOwnPtr.h"

namespace blink {

static const int dashRatio = 3;  // Ratio of the length of a dash to its width.

void StrokeData::setLineDash(const DashArray& dashes, float dashOffset) {
  // FIXME: This is lifted directly off SkiaSupport, lines 49-74
  // so it is not guaranteed to work correctly.
  size_t dashLength = dashes.size();
  if (!dashLength) {
    // If no dash is set, revert to solid stroke
    // FIXME: do we need to set NoStroke in some cases?
    m_style = SolidStroke;
    m_dash.reset();
    return;
  }

  size_t count = !(dashLength % 2) ? dashLength : dashLength * 2;
  OwnPtr<SkScalar[]> intervals = adoptArrayPtr(new SkScalar[count]);

  for (unsigned i = 0; i < count; i++)
    intervals[i] = dashes[i % dashLength];

  m_dash = SkDashPathEffect::Make(intervals.get(), count, dashOffset);
}

void StrokeData::setupPaint(SkPaint* paint, int length) const {
  paint->setStyle(SkPaint::kStroke_Style);
  paint->setStrokeWidth(SkFloatToScalar(m_thickness));
  paint->setStrokeCap(m_lineCap);
  paint->setStrokeJoin(m_lineJoin);
  paint->setStrokeMiter(SkFloatToScalar(m_miterLimit));

  setupPaintDashPathEffect(paint, length);
}

void StrokeData::setupPaintDashPathEffect(SkPaint* paint, int length) const {
  float width = m_thickness;
  if (m_dash) {
    paint->setPathEffect(m_dash);
  } else {
    switch (m_style) {
      case NoStroke:
      case SolidStroke:
      case DoubleStroke:
      case WavyStroke:  // FIXME:
                        // https://code.google.com/p/chromium/issues/detail?id=229574
        paint->setPathEffect(0);
        return;
      case DashedStroke:
        width = dashRatio * width;
        // Fall through.
      case DottedStroke:
        // Truncate the width, since we don't want fuzzy dots or dashes.
        int dashLength = static_cast<int>(width);
        // Subtract off the endcaps, since they're rendered separately.
        int distance = length - 2 * static_cast<int>(m_thickness);
        int phase = 1;
        if (dashLength > 1) {
          // Determine how many dashes or dots we should have.
          int numDashes = distance / dashLength;
          int remainder = distance % dashLength;
          // Adjust the phase to center the dashes within the line.
          if (numDashes % 2) {
            // Odd: shift right a full dash, minus half the remainder.
            phase = dashLength - remainder / 2;
          } else {
            // Even: shift right half a dash, minus half the remainder.
            phase = (dashLength - remainder) / 2;
          }
        }
        SkScalar dashLengthSk = SkIntToScalar(dashLength);
        SkScalar intervals[2] = {dashLengthSk, dashLengthSk};
        paint->setPathEffect(
            SkDashPathEffect::Make(intervals, 2, SkIntToScalar(phase)));
    }
  }
}

}  // namespace blink
